1. Field of the Invention
The present invention relates to agricultural harvesters, and, more specifically to harvesters for grain and protection of harvesting equipment.
2. Description of the Related Art
An agricultural harvester known as a “combine” is historically termed such because it combines multiple harvesting functions with a single harvesting unit, such as picking, threshing, separating and cleaning. A combine includes a header which removes the crop from a field, and a feeder housing which transports the crop matter into a threshing rotor. The threshing rotor rotates within a perforated housing, which may be in the form of adjustable concaves and performs a threshing operation on the crop to remove the grain. Once the grain is threshed it falls through perforations in the concaves onto a grain pan. From the grain pan the grain is cleaned using a cleaning system, and is then transported to a grain tank onboard the combine. A cleaning fan blows air through the sieves to discharge chaff and other debris toward the rear of the combine. Non-grain crop material such as straw from the threshing section proceeds through a residue system, which may utilize a straw chopper to process the non-grain material and direct it out the rear of the combine. When the grain tank becomes full, the combine is positioned adjacent a vehicle into which the grain is to be unloaded, such as a semi-trailer, gravity box, straight truck, or the like; and an unloading system on the combine is actuated to transfer the grain into the vehicle.
More particularly, a rotary threshing or separating system includes one or more rotors which can extend axially (front to rear) or transversely within the body of the combine, and which are partially or fully surrounded by a perforated concave. The crop material is threshed and separated by the rotation of the rotor within the concave. Coarser non-grain crop material such as stalks and leaves are transported to the rear of the combine and discharged back to the field. The separated grain, together with some finer non-grain crop material such as chaff, dust, straw, and other crop residue are discharged through the concaves and fall onto a grain pan where they are transported to a cleaning system. Alternatively, the grain and finer non-grain crop material may also fall directly onto the cleaning system itself.
A cleaning system further separates the grain from non-grain crop material, and typically includes a fan directing an airflow stream upwardly and rearwardly through vertically arranged sieves which oscillate in a fore and aft manner. The airflow stream lifts and carries the lighter non-grain crop material towards the rear end of the combine for discharge to the field. Clean grain, being heavier, and larger pieces of non-grain crop material, which are not carried away by the airflow stream, fall onto a surface of an upper sieve (also known as a chaffer sieve) where some or all of the clean grain passes through to a lower sieve (also known as a cleaning sieve). Grain and non-grain crop material remaining on the upper and lower sieves are physically separated by the reciprocating action of the sieves as the material moves rearwardly. Any grain and/or non-grain crop material remaining on the top surface of the upper sieve are discharged at the rear of the combine. Grain falling through the lower sieve lands on a bottom pan of the cleaning system, where it is conveyed forwardly toward a clean grain auger.
The clean grain auger conveys the grain to a grain tank for temporary storage. The grain accumulates to the point where the grain tank is full and is discharged to an adjacent vehicle such as a semi trailer, gravity box, straight truck or the like by an unloading system on the combine that is actuated to transfer grain into the vehicle.
Grain tanks for combines are often fitted with powered covers or extension that may be electrically, hydraulically or pneumatically powered. These covers or extensions can be linked to other movable grain tank components. If these components are moved when the grain tank is in a totally full position, damage to the equipment can result.
The possibility for the operator of the combine to determine whether the grain tank is full becomes a challenge when the operator is focused on navigating the combine and its harvesting components properly through a field. Some current combines provide a method of determining grain tank fullness by a transparent window, but this requires frequent distraction from the forward direction of the combine. Other approaches utilize contact sensors to provide a reading of the fullness of the tank depending upon how far up in the tank the contact sensor is located. Frequently these sensors are at three quarters and full capacity. While this somewhat serves the purpose of determining fullness, it does not give the operator an indication of how rapidly the tank is being filled, which would enable the operator to coordinate with a transport vehicle.
While some approaches have utilized non-contact sensors, they do not coordinate the sensors with the fullness of the tank to provide equipment protection.
An additional limitation of the prior art non-contact sensors, especially in the case of ultrasonic non-contact sensors, is that the grain tank is made from highly reflective structural sheet steel so that the ultrasonic waves sent out to determine distance of the pile have multiple reflections when the grain tank is nearing its empty condition. On top of this, existing ultrasonic sensors have a dead band or a minimum distance to the sensor. Any closer than that, a measurement cannot be taken. Such a condition imposes installation problems because of the need for the sensor to be close to the highest point on a combine which can encroach on height limitations based on the overall equipment.
Accordingly what is needed in the art is a simplified and effective way of providing equipment protection for a grain tank of a combine.
Additionally, what is needed in the art is a more effective ultrasonic sensor that measures the height of grain within a grain tank.